1. Field of the Invention
The present invention relates to air cushions of the type comprising chambers filled with air formed between two films of thermoplastic material, and to devices for filling and sealing such air cushions.
2. Description of the Prior Art
U.S. Letters Pat. No. 3,660,189 suggests a system for forming and inflating air cushions in which (1) inflatable air cushions are prepared by fusing together two heat sealable films in discrete areas to define a plurality of chambers between the films with each chamber having an open inlet passageway; (2) the uninflated air cushions are shipped to the site of their intended use (e.g. such as a packaging line in a production facility); and (3) a device is then used to inflate and seal the cushions. This type of system is known to reduce bulk handling problems and the costs of shipping air which would otherwise result if the air cushions were inflated and sealed at a central production facility and were then shipped in an inflated condition to the site of their intended use. The inflatable cushion used in the system of U.S. Pat. No. 3,660,189, however, has large elongate preformed chambers positioned in side-by-side relationship, with the chambers having aligned open ends. The device for inflating the chambers must sequentially position the open ends of the chambers adjacent a fill nozzle and then preform extensive heat sealing operations to seal the inlet passageways to the chambers, and to divide the elongate chambers into smaller chambers of a more desired size. Thus the filling and sealing device requires a complex sealing mechanism, making it less simple and compact than might be desired; and the shapes of the chambers than can be produced are less variable than might be desired.